Less than two years after Massachusetts' 2006 reform law was implemented, 2.6 percent of residents were uninsured-the lowest proportion ever recorded in an American state. The state's individual mandate alone does not explain this result, since it is not enforced against adults with incomes at or below 150 percent FPL or children. During a multi-day site visit, researchers identified several factors contributing to Massachusetts' high enrollment, including an intensive marketing campaign; use of data to establish subsidy eligibility for newly-insured residents; an integrated eligibility system serving multiple subsidy programs with a single application; and healthcare provider/community-based organization-driven application assistance.